1. Field of the Invention
The present invention relates to a physical quantity detection system for detecting an externally input physical quantity, a method for driving the physical quantity detection system, a solid-state image pickup device for detecting an amount of externally input light as a physical quantity, a method for driving the solid-state image pickup device, and an image pickup apparatus using the solid-state image pickup device.
2. Description of the Related Art
To detect an externally input physical quantity, physical quantity detection systems are used. For example, to detect an amount of incident light from a subject as a physical quantity, a solid-state image pickup device has been developed. In addition, to detect the capacitance formed between a detection electrode and a finger in accordance with the irregularities of a fingerprint of the finger as physical quantities, a fingerprint detection device (a capacitance detection device) has been developed.
Among various physical quantity detection systems, some solid-state image pickup devices, for example, include a pixel array unit in which pixels each including a photoelectric transducer are two-dimensionally arranged in a matrix. By scanning each of the pixels twice by changing the accumulation time period (exposure time period) of the signal, the solid-state image pickup devices read out two signals from each of the pixels using different sensitivities. Thereafter, the solid-state image pickup devices combines the two signals so as to increase the dynamic range (refer to, for example, Orly Yadid-Pecht and Eric R. Fossum, “Wide Intrascene Dynamic Range CMOS APS Using Dual Sampling,” IEEE TRANSACTIONS ON ELECTRON DEVICES, Vol. 44, No. 10, pp. 1721-1723, October 1997).